SQL - 将以前的值从一列传播到多个新列

Question

我有一个 Customer_ID 的 SQL 表，按年份显示付款。第一个（许多）客户如下所示：

 ID    Payment    Year
112          0    2004
112          0    2005
112          0    2006
112       9592    2007
112      12332    2008
112       9234    2011
112       5400    2012
112       7392    2014
112       8321    2015

请注意，缺少一些年份。我需要为每一行创建 10 个新列，显示过去 10 年的付款。结果表应如下所示：

 ID    Payment    Year   T-1  T-2  T-3  T-4  T-5  T-6  T-7  T-8  T-9 T-10   
112          0    2004  NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL
112          0    2005     0 NULL NULL NULL NULL NULL NULL NULL NULL NULL
112          0    2006     0    0 NULL NULL NULL NULL NULL NULL NULL NULL
112        952    2007     0    0    0 NULL NULL NULL NULL NULL NULL NULL
112       1232    2008   952    0    0    0 NULL NULL NULL NULL NULL NULL
112        924    2011  NULL NULL 1232  952    0    0    0 NULL NULL NULL 
112        500    2012   924 NULL NULL 1232  952    0    0    0 NULL NULL 
112        392    2014  NULL  500  924 NULL NULL 1232  952    0    0    0
112        821    2015   392 NULL  500  924 NULL NULL 1232  952    0    0

我很清楚这是数据的大量重复，因此看起来很奇怪。不过，我还是想做！ （正在为预测模型准备数据，其中将使用以前的付款（和其他信息）来预测当年的付款）

我不确定从哪里开始。我一直在研究使用数据透视，但不知道如何让它从客户上一年选择值。

我非常想在 SQL 中执行此操作。如果这不可能，我可以将表复制到 R 中 - 但 SQL 是我的首选。

非常感谢任何帮助。

Answer 1

如果你有完整的数据，你可以使用lag()：

select t.*,
       lag(payment, 1) over (partition by id order by year) as t_1,
       lag(payment, 2) over (partition by id order by year) as t_2,
       . . .
from t;

但是，对于您缺少中间年份的情况，left join 可能更简单：

select t.*,
       t1.payment as t_1,
       t2.payment as t_2,
       . . .
from t left join
     t t1
     on t1.id = t.id and
        t1.year = t.year - 1 left join
     t t2
     on t1.id = t.id and
        t1.year = t.year - 2 left join
     . . .;

Answer 2

我想你的朋友会是LAG

这是一个实现：

Declare @t table (
    ID int,
    Payment int,
    Yr int
)
Insert Into @t Values(112,0,2004)
Insert Into @t Values(112,0,2005)
Insert Into @t Values(112,0,2006)
Insert Into @t Values(112,9592,2007)
Insert Into @t Values(112,12332,2008)
Insert Into @t Values(112,9234,2011)
Insert Into @t Values(112,5400,2012)
Insert Into @t Values(112,7392,2014)
Insert Into @t Values(112,8321,2015)

Insert Into @t Values(113,0,2009)
Insert Into @t Values(113,9234,2011)
Insert Into @t Values(113,5400,2013)
Insert Into @t Values(113,8321,2015)


;with E1(n) as (Select 1 Union All Select 1 Union All Select 1 Union All Select 1 Union All Select 1 Union All Select 1 Union All Select 1 Union All Select 1 Union All Select 1 Union All Select 1)
,E2(n) as (Select 1 From E1 a, E1 b)
,E4(n) as (Select 1 From E2 a, E2 b)
,E5(n) as (Select row_number() over(order by isnull(null,1)) From E4 a, E1 b)
,IDYears as (
    Select z.ID, Yr = y.n
    From (
        Select 
            Id, 
            MinYear = min(Yr),
            MaxYear = max(Yr)
        From @t a
        Group By Id
        ) z
    Inner Join E5 y On y.n between z.MinYear and z.MaxYear
)

Select 
    *,
    [t-1] = Lag(B.Payment, 1) Over(Partition By a.ID Order By a.Yr),
    [t-2] = Lag(B.Payment, 2) Over(Partition By a.ID Order By a.Yr),
    [t-3] = Lag(B.Payment, 3) Over(Partition By a.ID Order By a.Yr),
    [t-4] = Lag(B.Payment, 4) Over(Partition By a.ID Order By a.Yr),
    [t-5] = Lag(B.Payment, 5) Over(Partition By a.ID Order By a.Yr),
    [t-6] = Lag(B.Payment, 6) Over(Partition By a.ID Order By a.Yr),
    [t-7] = Lag(B.Payment, 7) Over(Partition By a.ID Order By a.Yr),
    [t-8] = Lag(B.Payment, 8) Over(Partition By a.ID Order By a.Yr),
    [t-9] = Lag(B.Payment, 9) Over(Partition By a.ID Order By a.Yr),
    [t-10] = Lag(B.Payment, 10) Over(Partition By a.ID Order By a.Yr)
From IDYears a
Left Join @t b On a.ID = b.ID and a.Yr = b.Yr
Order By A.ID